1. Field of the Invention
The present invention relates to video signal processing, and, in particular, to computer-implemented processes, apparatuses, and systems for displaying multiple video streams on a single display monitor.
2. Description of the Related Art
It is desirable to provide a system for displaying multiple video streams on a single display monitor, where at least one of the video streams has a frame rate different from that of at least one of the other video streams.
Conventional systems for displaying video signals, such as the Intel.RTM. ActionMedia.RTM. II video system, comprise a pixel processor, a memory device, and a display controller. The pixel processor decodes encoded signals for a video stream and stores the decoded signals as unscaled bitmaps in the memory device. The pixel processor scales the unscaled bitmap signals for display and stores the scaled signals as scaled bitmaps back to the memory device. The display controller converts the scaled signals to a format suitable for display on a display monitor. In addition, the display controller optionally merges the converted video signals with graphics signals from the graphics processor and/or scales the bitmap signals yet again, before transmitting the merged signals to the frame buffer of the display monitor for display.
In order to display video signals at frame rates representative of real-time motion, the various components of such conventional video systems function concurrently. To support this concurrent processing, conventional video systems maintain a circular buffer of multiple bitmaps in the memory device for each video stream being processed. While the display controller is converting the scaled bitmap for video frame i (stored in a first position of the memory device), the pixel processor is generating the scaled bitmap for video frame i+1 (stored in a second position of the memory device) by scaling the unscaled bitmap for video frame i+1 (stored in a third position of the memory device). At the same time, the pixel processor is generating the unscaled bitmap for video frame i+2 (stored in a fourth position of the memory device), using the unscaled bitmap for video frame i+1 (stored in the third position of the memory device) as a reference for the decoding process. These bitmaps are overwritten in a circular fashion as a sequence of frames is processed.
To display multiple video streams at the same time in different windows within the raster of a display monitor, the total number of bitmaps that the video system maintains in the memory device is the product of the number of video streams and the number of bitmaps required for each video stream. In a conventional video system, the display of multiple video streams would be controlled by software.
If at least some of the video streams have different frame rates, then the software of the conventional video system would orchestrate the processing of each video stream separately to ensure that the proper video frames of each video stream are processed and displayed at the proper times and in the proper positions within the display raster. This is an unwieldy process. Moreover, the signal data and processing bandwidth limitations of conventional video systems limit the capability of such systems to display multiple video streams on a single display monitor.
What is needed is an improved video system for displaying multiple video streams on a single display monitor where at least some of the video streams have different frame rates.
It is accordingly an object of this invention to overcome the disadvantages and drawbacks of the known art and to provide a video system for displaying multiple video streams on a single display monitor where at least some of the video streams have different frame rates.
It is a further object of this invention to provide a video system for providing video conferencing capabilities between multiple remote participants.
Further objects and advantages of this invention will become apparent from the detailed description of a preferred embodiment which follows.